A Parliamentary inquiry into the sale of interest rate swaps to farmers is "one step away", West Coast MP Damien O'Connor has told the Sunday Star-Times.

Billions of dollars of complex swap loans sold to farmers in the run-up to the global financial crisis left many locked into paying inflated interest rates, or punitive break fees, even after interest rates crashed.

The swaps have deepened hardship in the farming community but there has been little public recognition of the issue outside of the pages of the Sunday Star-Times and its sister rural paper Straight Furrow.

Now the members of the primary production select committee, on which O'Connor serves, are summoning the Commerce Commission to give it an update on its preliminary investigation. That could happen as soon as next week.

After hearing what the commission tells the seven MPs, O'Connor said the committee would decide whether to begin its own inquiry and start asking witnesses to appear before it.

O'Connor said there was cross-party interest and understanding of the issue, and there was concern over the "delay" at the commission in deciding whether to investigate or not.

"Depending on their responses we will make a decision on who else to bring in before the select committee," he said.

Those who might be asked to appear include farmers' representatives and the banks.

"I still believe that unless they are committed to a full-blown inquiry, we should have a parliamentary inquiry into the matter," O'Connor said.

But he stressed the select committee would not be seeking to establish the legality of the swap sales. That was a job for the commission.

"Most of the committee members are aware first hand of swap loans and the experiences of individual farmers," O'Connor said.

"They understand the hard sell that went with the products and the complexity of them."

Committee chairman Shane Ardern said the swaps sales were an issue in rural New Zealand.

"I think it is an issue that is past, but of course there were some people who were effected by it at the time," he said.